RAPID CITY, S.D. (AP) — A team led by a South Dakota School of Mines and Technology assistant professor has discovered a new species of plant-eating dinosaurs that was a food source for an extinct relative of the crocodile.

Clint Boyd and two colleagues from other universities published fossil evidence of a crocodyliform feeding on small ornithopod dinosaurs. The findings, published this week in the academic journal PLOS ONE, are significant because dinosaurs are typically depicted as the dominant species, he said.

Small dinosaurs normally had worry about theropod dinosaurs like raptors or the T. rex, so the discovery adds a new dimension, Boyd said.

"You had your dominant riverine carnivores, the crocodyliforms, attacking these herbivores as well, so they kind of had it coming from all sides," he said.

Boyd's research started when he was looking through boxes of tiny bits of dinosaur bones at the Natural Museum of Utah in 2007. The bones, collected in 2002 from public lands within the Grand Staircase Escalante-National Monument in southern Utah, date back to the late Cretaceous period, which is toward the end of the age of dinosaurs.

Evidence shows bite marks on bone joints and proof of a crocodyliform tooth embedded in a dinosaur femur.

The dinosaur species has yet to be named.

Boyd worked with Stephanie Drumheller, of the University of Iowa and the University of Tennessee, and Terry Gates, of North Carolina State University and the Natural History Museum of Utah.